Endless tracks have been used on vehicles to increase the surface area on the ground upon which the vehicle traverses. This increased vehicle footprint results in a lower force per unit area on the ground being traversed than a conventional wheeled vehicle of the same weight.
Most tracked vehicles utilize an endless track driven by a sprocket in which teeth of the sprocket engage links of the track to drive the track and the vehicle forward. Road wheels are attached to the vehicle through independent suspensions and roll over the track as the vehicle traverses the ground. In this design, the road wheels do not drive the vehicle forward, only the sprocket is used for movement. The direct engagement of the sprocket does not allow for track slippage relative to the sprocket.
Track over tire systems have been used on vehicles used in agriculture, construction equipment, and off-highway systems in the past. These systems utilize an endless track disposed around the existing tires of the vehicle. The tires drive the vehicle forward by driving over the track. However, these systems experienced tires slipping relative to the tracks and greatly restrict, or completely lock, the suspension movement.
The following references were considered before filing this application: U.S. Pat. No. 6,296,328 to Wilkinson, U.S. Pat. No. 4,810,043 to McIntosh, U.S. Pat. No. 2,059,213 to Dorst, U.S. Pat. No. 1,660,100 to Smyth, U.S. Pat. No. 7,083,241 to Gunter, and U.S. Pat. No. 5,851,058 to Humbek et al.